Method and apparatus for transferring sheet-like objects

ABSTRACT

The invention relates to a method for transferring heavy loads, such as sheet-like objects, particularly anodes and cathodes, in electrolysis, the transfer apparatus comprising a lifting device ( 1 ) to which a stationary control housing ( 3 ) is attached; along the slide surfaces ( 6 ) of said control housing ( 3 ), there moves a control frame ( 5 ), and in said control frame there are arranged control shafts ( 7 ) along which a gripping element ( 8 ) is movable by the control surfaces ( 16 ) of said gripping element ( 8 ), so that the stationary control housing ( 3 ) is suspended from the lifting device ( 1 ) by means of at least three fastening elements ( 2 ) articulated at both ends. In addition, the invention relates to a transfer apparatus ( 4 ) for shifting heavy loads, particularly sheet-like objects, such as anodes and cathodes in electrolysis, said transfer apparatus comprising a control housing ( 3 ) attached to a lifting device ( 1 ), to which control housing there is attached to a control frame ( 5 ) movable along the slide surfaces ( 6 ) of the control housing ( 3 ), and in which control frame there are arranged control shafts ( 7 ) along which a gripping element ( 8 ) is movable by means of the control surfaces ( 16 ) of said gripping element, so that the control housing ( 3 ) is suspended from the lifting device ( 1 ) by at least three fastening elements ( 2 ) articulated at both ends.

FIELD OF THE INVENTION

The invention relates to a method for transferring heavy loads, such assheet-like objects, particularly anodes and cathodes in electrolysis, aswell as an apparatus for realizing said transfer.

BACKGROUND OF THE INVENTION

Electrolytic cleaning processes use large amounts of anodes and cathodesfor precipitating and decomposing metals. In these processes, sheet-likeelectrodes, anodes and cathodes, should be for instance transferred intoelectrolysis tanks and out thereof. In the tanks, the anode and cathodeshould be placed as near to each other as possible. When electrodes mustbe replaced for example in order to recover a precipitate created on acathode, the replacement is carried out by means of a batching elementthat first removes from the tank a desired number of electrodes, such ascathodes, and replaces them by an equal number of unprecipitatedstarting sheets. Nowadays electrode transport and their batching intotanks takes place by means of a tool, a spear, hanging from the hooks ofa lifting device. It has been observed that the lowering of electrodesinto tanks is difficult and requires, from time to time, manual guidingof the spear on the tank level. The electrodes to be lowered in thetanks easily collide against those already placed therein, because theintervals are short and irregular owing to the manual work. Collisionscause defects particularly in the starting sheets, and as a result shortcircuits are increased during electrolysis. Consequently, in order toavoid short circuits, the batching element and particularly the gripprovided in the batching element must be set in an advantageous positionwith respect to the electrodes in order to prevent any contact betweenthe separate electrodes. Among the drawbacks of the manual method, letus point out that it is slow and has a poor level of accuracy, and thatthe physical work is hard and dangerous. Among the drawbacks of thetraditional methods, let us also point out that the gripping elementswings during acceleration and slow-down, so that a precise alignment ofthe gripping element becomes difficult.

From the publication DE 3,508,195 there is known an apparatus where thetarget of alignment is provided with mechanical guide cones that performan accurate alignment as the gripping device is lowered down. Themovement of accurate alignment takes place on sliding and rollingsurfaces that also support the load and the gripping member.

From the publication FI 870,285 there is known a device where theloading member is provided with a stationary guide, along which aseparate housing moves supported by the loading arrangement. A grippingdevice is suspended from this housing by fastening elements, and thegripping device is shifted with respect to the housing in order toachieve an accurate alignment.

BACKGROUND OF THE INVENTION

The object of the invention is to alleviate the drawbacks of the priorart and to introduce a novel apparatus and method for transferring heavyloads, such as sheet-like objects, particularly anodes and cathodes inelectrolysis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Transfer apparatus

FIG. 2 Transfer Apparatus profile, viewed from the perspective along theA′ axis.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, excessive and harmful swinging movements ofthe transferring apparatus of sheet-like objects are advantageouslyprevented when aligning said apparatus and the load transferred by saidapparatus at the right spot by the tanks. The transfer apparatuscomprises a lifting device and a stationary control housing attachedthereto, said control housing being fastened to the lifting device by atleast three fastening elements that are articulated at both ends. Alongthe slide surfaces of the stationary control housing, there is arrangedan essentially vertically movable control frame. A gripping devicebelonging to the transfer apparatus moves along the vertical controlshafts of the control frame by means of the control surfaces of thegripping device. From above, the gripping device is suspended from thelifting device by means of ropes. The gripping device is movableessentially in the vertical direction both with respect to thestationary control housing and to the movable control frame.

Underneath the gripping device, there are provided gripping elementssuch as hooks that grip the sheet-like objects at corresponding spotswhen the objects, such as electrodes, should be moved. Owing to itsarticulated fastening elements, the control housing of the apparatus canbe horizontally shifted and rotated with respect to the lifting device.When the control frame is lowered down in the tank, the conical pinsarranged in at least two corners of the frame are inserted in the holesprovided in the tank in order to prevent the load from swinging duringthe lifting or lowering of the load. Respectively it is possible thatthe conical pins are arranged in the tank, and that the corners of thecontrol frame are provided with holes for the pins.

According to the invention, the control frame is attached, by at leastthree fastening elements such as rigging screws that are articulated atboth ends, to the lifting device. Now, preferably by using the structureaccording to the invention, the control frame attenuates the massinertial forces in the horizontal acceleration and slow-down of theload. By observing the length of the fastening element and the swingingangle thereof, the swinging of the load of the transfer apparatus can becontrolled. The fastening elements must be sufficiently short,preferably 200-500 mm, and the swinging angle of the fastening elementsis essentially larger than six degrees, in which case it advantageouslytends to return back to the vertical position during horizontalacceleration and slow-down. When the angle is set right, the shift ofthe whole apparatus in all directions is preferably restricted to +/−50millimeters, and the alignment is advantageously successful with theselimit values. The conical pins are made to fit into the holes designedfor them. In addition, by making the contacting surfaces of the slidesurfaces and the control frame as free of clearance as possible, theload is further prevented from swinging. Moreover, by adding in thecontrol frame an arrangement for locking the frame in its position forthe duration of lifting or lowering, more stability is achieved in alifting and lowering situation. By employing the transfer apparatusaccording to the invention, there also is achieved the advantage thatmanual help is not necessarily needed when setting the gripping deviceat the right spot at the tanks. The transfer apparatus is controlled bya computer at the right spot at the tanks, and visible swinging does notoccur.

The invention is described in more detail below with reference theappended drawing.

In a lifting device 1 according to FIG. 1, there is suspended by riggingscrews 2 a stationary control housing 3. The rigging screws 2 arepreferably short, with a length of 250 millimeters. Now, when using thestructure according to the invention, the control housing 3advantageously attenuates the mass inertial forces during horizontalacceleration and slow-down of the load. Thus, when the lifting device 1moves from tank to tank, the horizontal swinging of the load isprevented. The transfer apparatus 4 is shifted to the desired, spot bycomputer control. When necessary, the stationary control housing 3 canbe moved horizontally and turned around its central axis by means of theball joints provided at both ends of the rigging screws. The movablecontrol frame 5 belonging to the transfer apparatus 4 is arranged tomove essentially vertically along the slide surfaces 6 of the controlframe. The control frame 5 is provided with vertical control shafts 7,along which a gripping element 8, such as a spear, can be moved in thevertical direction by means of the control surfaces 16 of the spear. Thecontrol shafts 7 are arranged vertically on the opposite sides of thecontrol frame 5, and they are square in cross-section. Advantageouslythe control shafts are placed so that during the lifting of the controlframe 5, they do not strike the lifting device 1 located above. Fromabove, the spear 8 hangs from the lifting device and is attached theretoby ropes 9. Underneath the spear 8, there are provided gripping elements10 such as hooks, whereby the electrodes 11 are lifted from the tank orlowered therein.

When the transfer apparatus 4 should be aligned at the right spot at thetank 15, the location is first programmed by using a computer. When theapparatus is aligned at the right spot. the control frame 5 moving alongthe slide surfaces 6 of the control housing 3 is mechanically lowereddown, and at the tanks the conical pins 12 provided at least at twocorners of the control frame are inserted in the holes 13 meant for theconical pins, while the rigging screws 2 allow the necessary horizontaland turning motion of the control housing 3 with respect to the liftingarrangement. In shape, the holes are either round or elongate, and theirdiameter is preferably 100 millimeters. Advantageously the holes can bemanufactured already when the tank is being made. Thereafter a grippingelement 8, such as a spear, is lowered down by means of wires, so thatit slides supported by the control shafts of the control frame. Thehooks provided in the spear are fastened to brackets 14 provided in theelectrodes 11, and the electrodes are lifted to a suitable height.Thereafter the control frame is lifted up, and the lifting device 1transfers the electrodes 11 to the desired position.

1. A method for transferring loads comprising: a) positioning a transferapparatus over a tank, wherein said transfer apparatus comprises: alifting device; a control housing having essentially vertical memberswith slide surfaces attached to the lifting device from the uppermostpart of the control housing by means of at least three fasteningelements, the fastening elements each have a length of between 200-500millimeters and are articulated at both ends; a control frame havingessentially vertical members corresponding to the essentially verticalmembers of the control housing attached to the control housing andmovable along the slide surfaces of the control housing; wherein eachvertical member of the control frame contacts each correspondingvertical member of the control housing on at least two surfaces; atleast one control shaft attached to the control frame; and a grippingelement suspended by means of a moving element from the lifting device,wherein the gripping element is movable along the control surfaces ofthe control shaft; b) attaching sheet-like objects to the grippingelement; and c) transferring a load of the sheet-like objects.
 2. Themethod according to claim 1, wherein at least two conical pins are in atleast two corners of the control frame and each conical pin can beinserted in holes in the corners of the tank.
 3. The method according toclaim 1 wherein at least two conical pins are in at least two corners ofthe tank and each conical pin can be inserted in holes in the corners ofthe control frame.
 4. A transfer apparatus for transferring loadscomprising: a lifting device; a control housing having essentiallyvertical members with slide surfaces attached to the lifting device fromthe uppermost part of the control housing by means of at least threefastening elements, the fastening elements each have a length of between200-500 millimeters and are articulated at both ends; a control framehaving essentially vertical members corresponding to the essentiallyvertical members of the control housing attached to the control housingand movable along the slide surfaces of the control housing; whereineach vertical member of the control frame contacts each correspondingvertical member of the control housing on at least two surfaces; atleast one control shaft attached to the control frame; and a grippingelement suspended by means of a moving element from the lifting device,wherein the gripping element is movable along the control surfaces ofthe control shaft.
 5. The transfer apparatus according to claim 4,wherein at least two conical pins are in at least two corners of thecontrol frame, and each conical pin can be inserted in holes at thecorners of the tank.
 6. The transfer apparatus according to claim 4,wherein at least two conical pins are in at least two corners of thetank and each conical pin can be inserted in holes at the corners of thecontrol frame.